Automotive engineering
汽车工程
Look! No brakes
看！没有刹车
The use of regenerative braking in electric cars will change the way people drive, and also the market for components
在电动汽车上应用再生制动将改变人们的驾驶方式以及汽车配件市场

In 1894, when Louis Antoine Krieger started making electrically powered horseless carriages (pictured above), he introduced a feature that had appeared earlier on some electric trains. The motors that drove the front wheels of Krieger’s landaulet could operate in reverse, to work as generators when the driver slowed down. That let them recover kinetic energy from the vehicle’s forward motion, turn it into electricity and use this to top up the battery. But there was another benefit. The harvesting of this otherwise-lost energy also produced a handy braking effect, helping slow the vehicle without the driver having to apply the somewhat dodgy mechanical brakes.
一八九四年，路易斯·安托万·克里格（Louis Antoine Krieger）开始制造电力驱动的无马马车。他引入了一个先前已出现在一些电力火车上的功能。驱动车辆前轮的电机可以反向运转，在司机减速时变为发电机。这些电机可以回收车辆前进时产生的动能，将之转换为电力，为电池充电。但这还有一个好处。在收集这些原本被浪费掉的能量时还会产生有用的制动作用，司机无需使用有些复杂的机械制动装置就能让车慢下来。

Regenerative braking, as the technology Krieger used is now called, pretty much disappeared from road transport when electric power gave way to the internal-combustion engine. But, with sales of petrol- and diesel-powered vehicles peaking, and scores of new electric and hybrid cars appearing on the market, it is staging a comeback. Its principal advantage is that it increases the distance a vehicle is able to travel between charges. For example, according to its makers Audi, regeneration contributes 30% of the 400km maximum range of the firm’s e-tron suv. But regen braking, as it is known for short, also promises to do for the brake pedal what automatic gear boxes did for the clutch, and thus to make driving a one-pedal experience.
克里格曾使用的这项技术如今被称作再生制动，在电力被内燃机取代时几乎从道路交通中消失。但是，随着汽油和柴油车销量见顶而新的电动和混合动力车进入市场，它又东山再起。它的主要好处是延长车辆两次充电之间的行驶里程。例如，奥迪声称，它制造的e-tron SUV 的最大续航里程为400 公里，其中30%由再生制动提供。但是再生制动也有可能替代刹车踏板，就像自动变速箱替代离合器那样，从而让人们驾驶时只踩一个踏板就够了。

As Martin Tolliday, an automotive expert at Ricardo, a British engineering consultancy, observes, regenerative systems already encourage a different way of driving. Some cars, such as the Tesla Model 3, permit the driver to choose levels ranging from mild to aggressive. Mild lets the car coast more freely. Aggressive pulls the car up more sharply and recovers the most energy. Carmakers put sensors in such vehicles to turn on the brake lights once the force of regen braking reaches a level similar to that of conventional braking.
英国工程咨询公司里卡多（Ricardo）的汽车专家马丁·托里迪（Martin Tolliday）认为，再生制动系统已经促成了一种不同的驾驶方式。某些车如特斯拉Model 3能让驾驶者选择从温和到激进的不同刹车模式。在温和模式下汽车可以更自如地滑行。激进模式则会更迅猛地刹车并回收大部分能量。汽车制造商在这类车辆中安装了传感器，当再生制动力达到和传统刹车差不多的力度时就会亮起刹车灯。

Regeneration also permits braking methods to be blended. When a driver lightly touches the brakes in some models, it is not the friction brakes that are applied initially, but regen braking instead. Nissan, a Japanese firm, has taken this idea furthest. The latest version of its Leaf electric car features a switch that activates what it calls the ePedal. This combines acceleration and braking into a single action. As with other electric cars, when the driver relaxes pressure on the pedal, regenerative braking takes over. With an ePedal, though, if he takes his foot off altogether, the friction brakes are eventually applied as well.
再生制动还可以实现不同刹车方式混用。在某些车型上，如果驾驶者轻踩刹车，最先介入的不是摩擦式刹车，而是再生制动。日本汽车公司日产最充分地实践了这一理念。最新款的聆风（Leaf）电动车配备了一个开关，可以启动日产所说的ePedal 的模式。这种模式把加速和刹车融合成了一个动作。和其他电动汽车一样，当驾驶者放松踏板，再生制动会启动。而在 ePedal 模式下，如果驾驶者完全松开踏板，摩擦刹车最终也会启动。

The Leaf still has a brake pedal, but it is there for use only in extremities. In normal road conditions Nissan reckons the ePedal can meet 90% of a driver’s deccelaration needs and, particularly in heavy traffic, it avoids his having to shift his foot constantly from one pedal to another. Once he has got used to it, he rapidly learns how to play the ePedal when approaching junctions or stationary traffic ahead, and can bring his vehicle to a standstill without ever pressing the brake. He need not do so even going downhill. On inclines, the car will hold itself stationary until the ePedal is pressed, at which point it will set off again.
聆风仍然保留了刹车踏板，但只在极端情况下使用。日产认为，在正常路况下，ePedal 能满足驾驶者 90%的减速需求，还可省去在两个踏板间不断切换的麻烦，这在堵车时尤其有用。一旦习惯后，驾驶者很快就可学会在接近交叉路口或者静止的车流时使用ePedal，并能够不踩刹车就把车停稳。即使下坡时都不需要踩刹车。在坡道上，车会自动停稳，在ePedal 被踩下时才会再次启动。

Nor are drivers the only people who will be affected by the rise of regen braking. So, too, will those who service cars and who make components for them. Conventional brakes work by clamping a set of friction pads onto a disc on the wheel hub. The result of this friction is wear and tear, so pads and discs need to be replaced at frequent intervals. Regen braking means those components may last the lifetime of the vehicle. Some taxi drivers of elderly Toyota Prius hybrids reckon they are running on their vehicle’s original set of brake pads, even with a million kilometres on the odometer.
再生制动的兴起不只会影响驾车者，还会影响汽车维修厂和配件制造商。传统刹车使用一套摩擦片夹住汽车轮毂上的刹车盘。这样的摩擦会产生磨损，所以刹车盘和片需要频繁更换。有了再生制动，可能在一辆车的整个寿命期内都无需更换这些部件。一些开早期丰田普锐斯混动汽车的出租车司机相信车里用的还是原配的刹车片，就算里程表已经跑到了100 万公里。

Whether and when the brake pedal will disappear completely remains to be seen. Mr Tolliday thinks it is likely to happen eventually. Already, a number of cars use auto-braking, in which radar sensors apply the brakes if a vehicle gets too close to the one in front. In such a situation, if he is driving at all, a motorist with a single pedal could simply remove his foot and let the sensors work out how best to brake without the vehicle losing control of itself.
至于刹车踏板是否会彻底消失、何时会消失，还有待观察。托里迪认为这最终是有可能实现的。很多车已经在使用自动刹车，当车与前方的车距离过近时，雷达传感器会启动刹车。在这种情况下，如果当时司机还在操控汽车，在只有一个踏板的时候他可以直接松开踏板，让传感器决定如何最好地刹车而不会让车失控。

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